Effect of Fibrous Jacket on Behavior of RC Columns

This paper presented an extensive study about the strengthening of RC square short columns with high strength concrete jackets reinforced with steel fiber. The aim of this study is to investigate the effect of confinement by fibrous jacket on the behavior of RC column. A comparative study is performed on 23 square columns (six of them were unconfined columns where the remaining seventeen were confined columns) with varied parameters such as steel fibers ratio and type, jacket thickness, partial and full strengthening, type of confining jacket (hoop and composite), use of epoxy as bond material between the concrete column and strengthening jacket, and length parameter. The test results showed that the strengthened columns showed a significant improvement in the ultimate stress, load-carrying capacity, maximum strain, ductility, and energy absorption. Increase the steel fibers ratio (1, 1.5 and 2%) increased the ultimate stress by (22.5, 12.3 and 12.5%) respectively. The use of epoxy as bond material enhanced the ultimate stress by an average improvement by (55%). Composite case in the strengthening enhanced the load-carrying capacity larger than hoop case by (28.7 and 42%) for FRC jackets with hooked and straight fibers respectively but in case of stress capacity, hoop jacket carries stresses more than composite according to the stressed cross-sectional area. Increase jacket thickness (25 and 35 mm) enhanced the ultimate stress by (28.7 and 15.5%) respectively. Partial strengthening has a good enhancement in the ultimate load but was less than full strengthening. Increase the length by (25 cm) decreased the enhancement in load capacity of the column with hoop jacket by (45.3%). Concrete jackets enhanced Energy absorption and ductility which improved the deformation capacity. The compressive behavior of stub concrete columns was also modeled, simulated, and analyzed numerically by a 3D nonlinear finite element model. The verification process was performed against the reported data of the experimental test which proved the results of experimental results and showed a good agreement between experimental and numerical outcomes

BEHAVIOR OF CONCRETE MIXES USING RECYCLED AGGREGATE CONFINED WITH STEEL SECTIONS

Recycled Concrete Aggregate (RAC) is a form of recycled concrete that has been studied for green building for the past 50 years. It can be used to create strong structures, such as seismic retrofitting of earthquake-prone structures. Studies have attempted to experimentally study the effect of using recycled aggregate in concrete, but the literature lacks the use of recycled concrete aggregate rapped with steel rings. This study examines the behavior of circular concrete columns with different percentages of recycled aggregate. It examines the behavior of a column with different percentages of recycled aggregate, one without jacketing, one with partial jacketing, and one with full jacketing. The suggested approach is stimulated, and the samples are modeled using ABAQUS software to demonstrate a comparison between experimental and numerical analysis. The study on Behavior of Concrete Mixes Using Recycled Aggregate Confined with Steel Sections is pivotal for sustainable construction, conserving resources, and lowering carbon emissions. It also aligns with circular economy principles and compliance with sustainability regulations, fostering eco-friendly, cost-effective practices. Furthermore, the incorporation of jacketing and steel sections not only supports sustainability but also strengthens communities by enhancing earthquake and heavy load resistance, ensuring both environmental responsibility and the safety of structures in vulnerable regions. These results have to be adopted for their clear sustainability benefits, including resource conservation and waste reduction. Furthermore, the cost savings associated with using recycled aggregates make it economically attractive. Lastly, the enhanced mechanical properties of concrete contribute to more durable and resilient construction materials, aligning with both environmental, safety, and economic objectives

Repair and Strengthening of Reinforced Concrete Beams

Repair and strengthening of damaged or vulnerable reinforced concrete structures is important in order to guarantee the safety of residents or users. Beams are important structural elements for withstanding loads, so finding the efficient repair and strengthening methods are necessary in terms of maintaining the safety of the structures. This research study investigated various repair, retrofit, and strengthening techniques for reinforced concrete beams. The comparison and summary of each repair and strengthening method are provided in this thesis. The thesis involves the literature review of current experimental test of repair and strengthening techniques for reinforced concrete beams. The experimental studies were summarized by describing the specimens and loading details, All the methods in the research were categorized into five chapters: section enlargement and concrete jacketing, external reinforcement, steel plates, unbonded-type strengthening, and concrete repairs. The installation procedures were summarized and the advantages, shortcomings, and considerations of each method were also discussed in the thesis.No embarg

Flexural strengthening of reinforced concrete beams using hybrid fibre reinforced engineered cementitious composite

In this study, flexural strengthening of reinforced concrete (RC) beams using steel and polyvinyl-alcohol hybrid fibre reinforced engineered cementitious composite (SPH-ECC) with embedded steel reinforcement bars is proposed. The effectiveness of the strengthening was investigated by experimental and numerical studies. The flexural behaviours of one unstrengthened 3500 mm long, 200 mm wide, and 325 mm deep RC beam and three RC beams strengthened with different configurations of 50 mm thick SPH-ECC layer(s) were studied by conducting four-point bending tests. Detailed flexural behaviours in terms of peak load, failure mode, load-deflection curve, cracking patterns, interfacial bond-slip, strain distribution and ductility of the tested beams were studied and compared. Experimental results showed that both the flexural strength of strengthened beams, which were in the range of 125% to 210% of the unstrengthened control beam, and the interfacial bond-slip behaviours between concrete and SPH-ECC was highly depended to the strengthening configuration used. Crack width control ability of the beams was also improved by using SPH-ECC. A finite element (FE) procedure using surface-to-surface cohesive model was also developed to model the flexural behaviours of the strengthened beams. Comparison with experimental results demonstrated that the proposed FE model could accurately predict the flexural behaviours including interfacial bond-slip between the SPH-ECC layers and the RC beam part of the strengthened beams

Analysis of reinforced concrete beams strengthened using concrete jackets

Analysis of jacketed Reinforced Concrete (RC) beams considering the interfacial slip effect is a complicated problem. In the current practice, slip is neglected in the analysis and monolithic behavior is assumed in the jacketed section resulting in higher estimates of stiffness and/or capacity. Engineers need simplified yet robust tools to predict the actual behavior of jacketed RC beams. This paper provides a simplified method to analyze jacketed RC beams taking into account the interfacial slip distribution and the actual nonlinear behavior of both concrete and steel. An iterative calculation algorithm is developed to determine the moment-curvature and load-deflection curves of the jacketed beams. The developed method provides an evaluation of the slip and shear stress distributions, which allow assessing the influence of surface roughness conditions. The developed method is utilized to conduct an extensive parametric study, which resulted into modification factors to calculate the capacity and deformations of strengthened beams while accounting for interfacial slip

Assessment of the flexural behavior of reinforced concrete beams strengthened with concrete jackets

Analysis of continuous jacketed Reinforced Concrete (RC) beams requires accounting for the nonlinear behavior of the interface and the materials as well as redistribution of moments. This kind of analysis is complex and require an advanced level of knowledge and experience to perform. Engineers need simplified yet robust tools to practically predict the actual behavior of jacketed RC beams. In the current practice, slip is neglected in the analysis and monolithic behavior is assumed for the jacketed section, which result in higher estimates of stiffness and/or capacity. This paper provides a simplified method to analyze continuous jacketed RC beams taking into account the interfacial slip distribution and the actual nonlinear behavior of both concrete and steel. An iterative calculation algorithm is developed to determine the moment–curvature curves of a jacketed beam at different sections. The developed method allows the evaluation of interfacial slip and shear stress distributions in ductile reinforced concrete beams. The developed method is utilized to conduct an extensive parametric study, which resulted into modification factors that can be used to calculate the capacity and deformations of a strengthened beam considering the interfacial slip

Mejora de la respuesta sísmica del Colegio Felipe Salaverry usando reforzamiento de encamisado de columnas departamento de Ayacucho 202

En la actualidad en el Perú existen numerosas edificaciones educativas con una serie de problemáticas estructurales que ponen en riesgo, o al menos en duda su capacidad resistente frente a la acción de sismos de gran magnitud, que, de acuerdo con la Universidad Nacional de Ingeniería y el CISMID, es muy probable ocurra con una magnitud superior a 8.0 Mw. Esto pone en riesgo, no solo la integridad de la vida de sus ocupantes, y la interrupción de los servicios brindados, sino también, la función como refugio que se le asigna a este tipo de estructuras frente a la ocurrencia de un sismo de gran impacto. Esta realidad afecta especialmente al colegio Felipe Salaverry ubicada en el departamento de Ayacucho, que es una estructura diseñada y construida con base en pórticos de concreto armado, un sistema que en general posee muy baja rigidez lateral frente a la acción de sismos. Para esto se ha implementado la metodología basada en el análisis estático no lineal y basada en diseño por desempeño sísmico, además, se han propuesto un método de reforzamiento basado en el encamisado de columnas que permite un incremento sustancial de la rigidez lateral. Los resultados encontrados muestran que, en efecto, la rigidez lateral, y por tanto el desempeño sísmico de la estructura analizada tuvo una mejora sustancial